This installation and documentation was possible, thanks to @marcobrianza
NB: Grafana binaries are specific to the CPU architecture, therefore, swapping SD cards between RPi 1 <> 2+, is not recommended

Roon Extension Manager:
At startup the Roon Extension Manager accesses a repository containing the community developed extensions. Via Settings->Extensions within Roon the repository can be viewed and an extension can be selected to perform a certain action.Many thanks to @JanKoudijs for contributing this into DietPi

If you require write access from other applications (eg: Plex subtitle downloads), you'll also need to set the file/folder creation mask to allow this.

In the the web interface, select Settings

Toggle to Advanced settings slider (enable it)

Under Media Management tab, scroll down to the bottom of the page under Permissions, set the following values:

Save changes

Add a music:

Simply select Artist > Add New

Type a name of the artist you wish to find

Once found, under root folder, use the following location /mnt/dietpi_userdata/downloads

Change any other settings as required, then select Add

Recommended: Protect your privacy with a VPN:
Although we enable forced encryption on all our BitTorrent clients, if you wish to ensure complete privacy and peice of mind for all your downloaded content, using a VPN is critical.

Nextcloud Talk:
Video calls hosted on your own Nextcloud instance. The TURN server "coturn" will be installed and configured as well to allow reliable video calls through outside the local network, NAT and firewall setups.

Also installs:

Nextcloud

coturn

Install Notes:

During installation you will be asked to enter the external server domain and a port, that you want to use for the coturn TURN server. Note that you need to forward the chosen port and/or open it in your firewall.

If HTTPS was or is enabled via dietpi-letsencrypt, coturn will be configured to use the LetsEncrypt certificates for TLS connections on the chosen TURN server port automatically.

coturn by default will listen to non-TLS requests as well on the port configured in /etc/turnserver.conf. You can force TLS/control this by switching port forwarding in your router and/or opening/dropping ports in your firewall.

coturn logging by default is disabled via /etc/default/coturn command arguments, since it is very verbose and produces much disk I/O. You can enable and configure logging via /etc/turnserver.conf, if required.

DietPi-NordVPN:
DietPi-NordVPN is a combination of OpenVPN installation and DietPi front end GUI. Allowing all NordVPN users to quickly and easily connect to any NordVPN server in TCP or UDP, using only open source software.

Requires NordVPN Subscription:
Although we enable forced encryption on all our BitTorrent clients, if you wish to ensure complete privacy and peice of mind for all your downloaded content, using a VPN is critical.NordVPN. Offers unlimited bandwidth, zero logging and upto 6 devices on 1 account.

Usage:
Once installed using dietpi-software:

Simply run dietpi-nordvpn to use the GUI, allowing you to setup your connection.

DietPi will also automatically start and connect the VPN during system boot.